Skip to main content
cancel
Showing results for 
Search instead for 
Did you mean: 

Earn the coveted Fabric Analytics Engineer certification. 100% off your exam for a limited time only!

Reply
IamTDR
Responsive Resident
Responsive Resident

Power Query Slow Down Question

In general, I find at times Power Query can run very slow.  Generally, what could be the common issues?  I understand the datawarehouse table size (records and fields) and doing merges can cause slow down but at other times these same tables run just fine.  Latest example I have is a query running very slow.  Almost 20 minutes between each step.  The part I dont understand is, the first step was to limit the table to only 100 records.  Still the query runs very slow. 
I questioned my IT department to see if something else is running on our datawarehouse that would cause this slowdown.  They respond that nothing out of the norm is.  So my question is what else could be slowing down my query?
Do I need to adjust/clear settings?

Thanks in advance

2 REPLIES 2
v-eqin-msft
Community Support
Community Support

Hi @IamTDR ,

 

What's your data source? Did you load multiple data sources in a single .pbix file? If your data is huge, it is recommended to avoid importing the data and use direct query first.

 

the first step was to limit the table to only 100 records.  Still the query runs very slow. Such performance is strange.

Since to my knowledge, It's always recommended to filter your data in the early stages of your query or as early as possible. It's also a best practice to filter out any data that isn't relevant for your case. This will let you better focus on your task at hand by only showing data that’s relevant in the data preview section. 

 

You may try:

1. Optimize the current query model and delete unnecessary columns in the model.

2. Use Performance Analyzer to examine report element performance in Power BI Desktop

3. If you don't need to preview all of the queries you can turn off Background Data; go to Query Options > Current Workbook: Data Load > uncheck 'Allow data preview to download in the background'.

4. Consider turning off Data Privacy Settings

5. Or try to use Table.Buffer() , which might or might not make your queries run faster. In some cases, it can make your queries run more slowly due to the added cost of reading all the data and storing it in memory, as well as the fact that buffering prevents downstream folding.

 

Refer to:

Best practices when working with Power Query - Power Query | Microsoft Docs

Any way to speed up really slow refresh times in Power Query?

Speed Up Data Refresh Performance In Power BI Desktop Using Table.View

 

 

Best Regards,
Eyelyn Qin
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.

Thanks for the reply.  I am wondering if this was due to my organization as well.  My source is our organizations datawarehouse.  Just strange how at times its very fast and other times simple steps take a very long time.

Helpful resources

Announcements
April AMA free

Microsoft Fabric AMA Livestream

Join us Tuesday, April 09, 9:00 – 10:00 AM PST for a live, expert-led Q&A session on all things Microsoft Fabric!

March Fabric Community Update

Fabric Community Update - March 2024

Find out what's new and trending in the Fabric Community.

Top Solution Authors
Top Kudoed Authors